A horizontal comparative study of a number of the microflora members in interproximal plaques sampled from surfaces which are sound or which have small lesions has indicated that the systems are highly multi-variable. Therefore, the bivariate analyses procedures usually used are inadequate to cope with the data. It is proposed to develop expertise for computer usage in order to perform the needed multi-variable analyses. Initial data analyses will be by multiple regression techniques which are considered of value because of the potential utility of the beta coefficients to hierarchal considerations of each variable, and because of the elicitation of "suppressor" variables. A replicate horizontal study will then be performed to determine the reproducibility of the data and of the analyses. If successful, the multiple regression equations developed can then be used for a longitudinal study in order to estimate the predictive value of the variables and caries experience.